Cyanoacrylate adhesive composition

ABSTRACT

A cyanoacrylate adhesive composition is disclosed which has a lowered adhesion to the skin and contains at least one compound selected from the groups mentioned below and an anionic polymerization accelerator:  
     A: An aliphatic alcohol having an aliphatic group in which 6 or more carbon atoms are directly bonded with each other;  
     B: An aliphatic carboxylic acid ester having an aliphatic group in which 6 or more carbon atoms are directly bonded with each other;  
     C: An aliphatic carboxylic acid ester having at least 2 aliphatic groups in which 4 or more carbon atoms are directly bonded with each other; and  
     D: A carboxylic acid ester of a carbocyclic compound having, in a carboxylic acid residue or alcohol residue, an aliphatic group in which 5 or mare carbon atoms are directly bonded with each other.

[0001] The present invention relates to a cyanoacrylate adhesive composition having a weakened adhesion to the skin and can widely be used in various industries, medical fields, leisure fields, and household fields where cyanoacrylate adhesives are utilized as an instantaneous adhesive.

[0002] Cyanoacrylate adhesives containing 2-cyanoacrylate as a principal component have favorably been used in various industries, medical fields, leisure fields, and household fields as an instantaneous adhesive, since the adhesives have the property that 2-cyanoacrylate as a principal component is readily anionic-polymerized to rapidly cure in the presence of a very small amount of moisture or a basic substance.

[0003] However, 2-cyanoacrylate adhesives have such problems that the adhesives bond a part of the skin with another part of the skin of a person who handles the adhesive or that the adhesives bond the skin with other adherends than the skin if the adhesives were used incorrectly, while the adhesives have such a convenient property that they can join glass, metal, plastic, wood, fabric, and paper instantaneously.

[0004] The troubles are caused by the existence of moisture and basic substances contained in sweat and secretions on the surface of human skin. The moisture and basic substances accelerate anionic polymerization of 2-cyanoacrylate adhesives so that the skin is readily bonded.

[0005] Since the skin adheres to another part of the skin or other adherends through 2-cyanoacrylate adhesives with a high bonding strength, if the adhered skin was forced to be torn off, the skin or subcutaneous tissue may be seriously injured.

[0006] Based on the background mentioned above, the development of an instantaneous adhesive is strongly desired, which lowers such a trouble that the adhesive adheres to the skin at the time of adhesion operation and which can be handled more easily and safely than conventional instantaneous adhesives.

[0007] As a result of the study to solve the problems mentioned above, it has been found that a cyanoacrylate adhesive composition containing at least one specific aliphatic alcohol, aliphatic carboxylic acid ester, or carboxylic acid ester of a carbocyclic compound has a low bonding rate on the skin, but bonds adherends other than the skin such as woods, plastics, rubbers, metals, and ceramics instantaneously.

[0008] The present invention relates to a cyanoacrylate adhesive composition having a lowered adhesion to the skin, which comprises at least one compound selected from the groups mentioned below and an anionic polymerization accelerator:

[0009] A: An aliphatic alcohol in which the aliphatic group contains 6 or more carbon atoms directly bonded with each other;

[0010] B: An aliphatic carboxylic acid ester in which the aliphatic group contains 6 or more carbon atoms directly bonded with each other;

[0011] C: An aliphatic carboxylic acid ester having at least 2 aliphatic groups in which the aliphatic group contains 4 or more carbon atoms directly bonded with each other; and

[0012] D: A carboxylic acid ester of a carbocyclic compound having an aliphatic group as a carboxylic acid residue or an alcohol residue, in which said aliphatic group contains 5 or more carbon atoms directly bonded with each other.

[0013] The adhesive composition of the present invention will be described in detail below.

[0014] A principal component of cyanoacrylate adhesives is a 2-cyanoacrylate. Various kinds of 2-cyanoacrylates can be used as a principal component even in the adhesive composition of the present invention as in conventional cyanoacrylate adhesives, and specific examples of the 2-cyanoacrylates include methyl, ethyl, chloroethyl, n-propyl, i-propyl, allyl, propargyl, n-butyl, i-butyl, n-pentyl, n-hexyl, cyclohexyl, phenyl, tetrahydrofurfuryl, heptyl, 2-ethylhexyl, n-octyl, n-nonyl, oxononyl, n-decyl, n-dodecyl, 2-ethoxyethyl, 3-methoxybutyl, 2-ethoxy-2-ethoxyethyl, butoxy-ethoxy-ethyl, 2,2,2-trifluoroethyl, or hexafluoroisopropyl ester of 2-cyanoacrylic acid.

[0015] Specific examples of the aliphatic alcohol, under the Group A mentioned above, having an aliphatic group in which 6 or more carbon atoms are directly bonded with each other include monohydric alcohols, such as n-hexyl alcohol, n-octyl alcohol, n-nonyl alcohol, 2-nonyl alcohol, decyl alcohol (decanol), lauryl alcohol (dodecyl alcohol/dodecanol), tridecyl alcohol (tridecanol), tetradecyl alcohol, pentadecyl alcohol, β-citronellol, 9-decene-1-ol, 1,1-dimethyl-5-methyl-6-heptene-1-ol, dihydromyrcenol, geraniol, 1,5-dimethyl-1-vinyl-4-hexene-1-ol, and ω-undecenyl alcohol. While alcohols mentioned above are preferable in the present invention, the aliphathic alcohol is not restricted to such alcohols.

[0016] The alcohol used in the present invention is an aliphatic alcohol having an aliphatic group in which 6 or more carbon atoms are directly bonded with each other. If all of the aliphatic groups in the molecule have 5 or less carbon atoms directly bonded with each other, the bonding rate on the skin becomes fast and troubles are caused at the time of adhesion operation so that such alcohols can not be used to achieve the purpose of the present invention.

[0017] Conversely, when the alcohol has, in its molecule, an aliphatic group in which 16 or more carbon atoms are bonded, the solubility of the alcohol in a cyanoacrylate becomes worse. Accordingly, aliphatic alcohols used for the present invention preferably have an aliphatic group in which 15 or less carbon atoms are directly bonded with each other, and more desirably the alcohols have an aliphatic group in which 8 to 15 carbon atoms, particularly, 9 to 15 carbon atoms are directly bonded with each other.

[0018] As will be clear from the specific examples mentioned above, the aliphatic group is preferably a hydrocarbon group (linear or branched polymethylene or polyolefin).

[0019] When the amount of the aliphatic alcohol to be added to the adhesive composition of the present invention is small, a sufficient inadhesiveness to the skin can not be obtained. When the amount is too much, however, the bonding rate on adherends other than the skin becomes slow, and thus, it is desirable to adjust the concentration of the alcohol in the cyanoacrylate adhesive composition to 10 to 40% by weight, and more desirably to 15 to 30% by weight.

[0020] Specific examples of the aliphatic carboxylic acid ester, under the Group B mentioned above, having an aliphatic group in which 6 or more carbon atoms are directly bonded with each other, and examples of the aliphatic carboxylic acid ester, under the Group C mentioned above, having at least 2 aliphatic groups in which 4 or more carbon atoms are directly bonded with each other include the following compounds:

[0021] Monocarboxylic acid ester

[0022] Cetyl 2-ethyl hexylate, methyl ester of coconut fatty acid, methyl laurate, isopropyl myristate, methyl caprate, methyl oleate, isobutyl oleate, octyl oleate, 2-ethylhexyl crotonate, octyl acrylate, decyl methacrylate, tridecyl methacrylate, lauryl methacrylate, and lauryl propiolate.

[0023] Polycarboxylic acid ester

[0024] Bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) maleate, dimethyl sebacate, bis(2-ethylhexyl) sebacate, bis(2-ethylhexyl) decamethylenedicarboxylate, 2,2,4-trimethyl-1,3-pentanediolmonoisobutylate, 2,2,4-trimethyl-1,3-pentanedioldiisobutylate, triglyceride 2-ethyl hexanoate, triglyceride caprylate, diglyceride caprylate, and triglyceride caprate.

[0025] Carboxylic acid ester having at least 2 aliphatic groups

[0026] Diisobutyl fumarate, diisobutyl maleate, tributyl acetyl citrate, and triglyceride caproate.

[0027] As explained above, the aliphatic carboxylic acid ester used in the present invention has an aliphatic group in which 6 or more carbon atoms are directly bonded with each other, or has at least 2 aliphatic groups in which 4 or more carbon atoms are directly bonded with each other. When all of the aliphatic groups in the molecule has 5 or less carbon atoms directly bonded with each other, or the aliphatic carboxylic acid ester does not have at least 2 aliphatic groups in which 4 or more carbon atoms are directly bonded each other, the bonding rate on the skin becomes high and troubles are apt to be caused at the time of adhesion.

[0028] However, when the aliphatic group present in the molecule has 16 or more carbon atoms directly bonded with each other, the solubility of the aliphatic carboxylic acid ester in a cyanoacrylate becomes poor. Thus, the number of the carbon atoms directly bonded in the aliphatic group is preferably 15 or less, and more preferably 8 to 13. The aliphatic carboxylic acid ester is preferably 150 to 2000 in terms of molecular weight.

[0029] Further, as to the aliphatic carboxylic acid ester having at least 2 aliphatic groups in which 4 or more carbon atoms are directly bonded with each other, the ester having at least 3 aliphatic groups are preferably used in the present invention.

[0030] The aliphatic carboxylic acid ester mentioned above is added in the cyanoacrylate adhesive composition preferably in an amount of 1 to 40% by weight, and more preferably 5 to 30% by weight, since when the amount is small, a sufficient inadhesiveness can not be obtained, while when the amount of the ester to be added is too large, the bonding rate on adherends other than the skin becomes slow.

[0031] The carbocyclic carboxylic acid ester, under the Group D, having, in a carboxylic acid residue or alcohol residue, an aliphatic group in which 5 or more carbon atoms are directly bonded with each other is an ester of a carbocyclic carboxylic acid with an alcohol. Specific examples of the acid and the alcohol include the following compounds:

[0032] Carbocyclic carboxylic acid

[0033] Benzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, o-chlorobenzoic acid, salicylic acid, anisic acid, vanillic acid, veratric acid, peperonylic acid, protocatechuic acid, gallic acid, syringic acid, cyclohexane carboxylic acid, 3-biphenyl carboxylic acid, 1,5-naphthalene dicarboxylic acid, 2-naphthalene hexanoic acid, 1,3,6-naphthalene triacetic acid, camphoric acid, phthalic acid, isophthalic acid, terephthalic acid, hemimellitic acid, trimellitic acid, trimesic acid, prehnitic acid, mellophanic acid, pyromellitic acid, benzene pentacarboxylic acid, mellitic acid, phenyl acetic acid, hydrocinnamic acid, γ-phenyl butyric acid, δ-phenyl-n-valerianic acid, ε-phenyl-n-capric acid, cinnamic acid, phenyl propiolic acid, homophthalic acid, o-phenylene diacetic acid, m-phenylene diacetic acid, p-phenylene diacetic acid, o-phenylene acetic acid-ε-propionic acid, cinamal malonic acid, ω-phenyl-n-propyl malonic acid, acetyl cumaric acid, and cochenilic acid.

[0034] Alcohol

[0035] n-pentyl alcohol, n-hexyl alcohol, n-octyl alcohol, 2-ethylhexyl alcohol, n-nonyl alcohol, isononyl alcohol, decyl alcohol, isodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, β-citronellol, 9-decene-1-ol, 1,1-dimethyl-5-methyl-6-heptene-1-ol, geraniol, 1,5-dimethyl-1-vinyl-4-hexene-1-ol, and ω-undecenyl alcohol.

[0036] In the carbocyclic carboxylic acid ester, under the Group D, used in the present invention, the aliphatic group in which 5 or more carbon atoms are directly bonded with each other may present in a carboxylic acid residue, for instance, between a carbon ring and a carboxyl group as a substituent on the carbon ring, or may exists in an alcohol residue. In the present invention, the ester prepared by using an alcohol having an aliphatic group in which 5 or more carbon atoms are directly bonded with each other is preferable, and specific examples of such ester include the following compounds.

[0037] Carbocyclic carboxylic acid ester

[0038] Dihexyl phthalate, diheptyl phthalate, dioctyl phthalate, bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, diisotridecyl phthalate, dipentadecyl phthalate, dioctyl terephthalate, diisononyl isophthalate, decyl toluylate, bis(2-ethylhexyl) camphorate, 2-ethylhexyl cyclohexyl carboxylate, 2-ethylhexylbenzoate, bis(2-ethylhexyl) pyromellitate, and tris(2-ethylhexyl) trimellitate.

[0039] If the carbocyclic carboxylic acid ester having only aliphatic group in which less than 5 carbon atoms are directly bonded with each other is used, the bonding rate of the adhesive to the skin becomes high and the purpose of the present invention can not be attained.

[0040] In order to bring the effect of the present invention into fully play, it is preferable to use a carbocyclic carboxylic acid ester having an aliphatic group in which 6 or more, more desirably 8 or more, particularly 9 or more carbon atoms are directly bonded with each other.

[0041] However, when the carbocyclic carboxylic acid ester having an aliphatic group in which too many carbon atoms are directly bonded with each other was used as the ester in the present invention, the solubility of the ester in a cyanoacrylate becomes poor, and there is a fear that troubles are produced in the preparation of the adhesive.

[0042] Thus, the carbocyclic carboxylic acid ester to be used in the present invention preferably has only aliphatic group in which less than 15 carbon atoms are directly bonded with each other, and more preferably less than 13 carbon atoms.

[0043] Specific examples of preferable carbocyclic carboxylic acid ester in the present invention include bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, diisotridecyl phthalate, and tris(2-ethylhexyl) trimellitate.

[0044] The amount of the carbocyclic carboxylic acid ester to be added in the present invention is preferably 1 to 40% by weight, and more preferably b to 30% by weight in the cyanoacrylate adhesive composition. When the amount is small, a sufficient inadhesiveness can not be obtained, while the amount is too much, the bonding rate on adherends other than the skin becomes slow.

[0045] It was known that when an anionic polymerization accelerator was blended in a cyanoacrylate adhesive, the bonding rate of the cyanoacrylate adhesive on the skin or on other substances became fast. However, as a result of the study by the present inventors, it has been found that when at least one specific aliphatic alcohol, aliphatic carboxylic acid ester, or carbocyclic carboxylic acid ester as well as an anionic polymerization accelerator were added together to a cyanoacrylate adhesive, the effect of increasing the bonding rate on the skin is low, while the effect of increasing the bonding rate on adherends other than the skin, such as woods, plastics, rubbers, and ceramics is excellent, leading to the preparation of an excellent adhesive of the present invention.

[0046] As the anionic polymerization accelerator to be used in the present composition, the following compounds are mentioned.

[0047] First, a polyalkylene oxide or its derivatives can be mentioned, and the known compounds such as disclosed in Japanese Examined Patent Publication (Kokoku) Nos. 60-37836, 60-26513, and 1-43790, and Japanese Unexamined Patent Publication (Kokai) Nos. 63-128088 and 3-167279 can all be used. Specific examples of the polymerization accelerator include the followings:

[0048] Polyalkylene oxide

[0049] Diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene-glycol, poly(1,3-propylene glycol), polytrimethylene oxide, polytetramethylene oxide, polyepichlorohydrin, poly(3,3-bis(chloromethyl) butylene oxide), polytetramethylene ether glycol, poly(1,3-dioxolane), poly(2,2-bis(chloromethyl) propylene oxide), ethylene oxide-propylene oxide block polymer, polyglycerins such as diglycerin, triglycerin, and tetraglycerin, formaldehyde condensation products, acetaldehyde condensation products, and trioxane polymers. Further, various kinds of polyalkylene oxides which are sold on the market as polyols for curing polyether urethanes can be used in the present invention.

[0050] Derivatives of a polyalkylene oxide

[0051] Derivatives of a polyalkylene oxide are represented by an ester of a polyalkylene oxide mentioned above with an acid or represented by an ether of the polyalkylene oxide with a hydroxy group-containing compound. While those derivatives are preferable, the derivatives are not restricted to them. Thus, the derivatives having a polyalkylene oxide structure in their molecule, such as ones having various kinds of substituents at their end and ones having another bonding portion in their molecule can better attain the purpose of the present invention.

[0052] As an acid which may constitute the ester, there may be mentioned acetic acid, propionic acid, butyric acid, isobutyric acid, pivalic acid, pentanoic acid, n-hexanoic acid, 2-methylpentanoic acid, n-octanoic acid, n-decanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, cyclohexyl carboxylic acid, cyclopentyl carboxylic acid, cyclopropyl carboxylic acid, acrylic acid, methacrylic acid, maleic acid, itaconic acid, naphthenic acid, benzoic acid, p-napthyl carboxylic acid, p-toluene carboxylic acid, furan carboxylic acid, p-chlorobenzoic acid, monochloroacetic acid, cyanoacetic acid, glycolic acid, lactic acid, phenyloxy propionic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, butane tetracarboxylic acid, aconitic acid, propane-1,2,3-tricarboxylic acid, citric acid, orthophthalic acid, isophthalic acid, trimellitic acid, and pyromellitic acid.

[0053] As a hydroxy group-containing compound which may constitute the ether, there may be mentioned methanol, ethanol, propanol, isobutanol, hexanol, cyclohexanol, 2-ethyloctanol, decanol, lauryl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, phenol, α-naphthol, β-naphthol, cresol, t-butyl phenol, octyl phenol, nonyl phenol, p-chlorophenol, resol, bisphenol A, 2-chloroethanol, ethylene cyanhydrin, trifluoroethanol, benzyl alcohol, 1,4-butane diol, 1,6-hexane diol, glycerin, sorbitol, hydrogenated bisphenol A, and trimethylol propane.

[0054] Specific examples of the ether as a polyalkylene oxide derivative include diethyleneglycol monoalkyl ether (as the alkyl, for instance, methyl, ethyl, propyl, or butyl may be used), diethyleneglycol dialkyl ether (as the alkyl, for instance, methyl, ethyl, propyl, or butyl may be used), polyethyleneglycol monoalkyl ether (as the alkyl, for instance, methyl, ethyl, propyl butyl, lauryl, cetyl, stearyl, or oleyl may be used), polypropyleneglycol monoalkyl ether (as the alkyl, for instance, methyl, ethyl, propyl, butyl, lauryl, cetyl, stearyl, oleil, or perfluoroalkyl may be used), polyethyleneglycol monoaryl ether (as the aryl, for instance, octylphenyl or nonylphenyl may be used), polyethyleneglycol dialkyl ether, polypropyleneglycol dialkyl ether, and polyethyleneglycol diaryl ether.

[0055] Specific examples of the ester as a polyalkylene oxide derivative include polyethyleneglycol monoalkyl ester (for example, acetate, trifluoroacetate, laurate, stearate, oleate, and methacrylate), polyethyleneglycol diester, polypropyleneglycol diester, bisphenol A-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), hydrogenated bisphenol A-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), trimethylol propane-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), glycerin-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), polyoxyethylene sorbitan ester, tetraoleic acid-polyoxyethylene sorbit addition product, adipic acid-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), trimellitic acid-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), isocyanate compound-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), phosphoric acid-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), silicic acid-polyalkylene oxide addition product (as the alkylene, for instance, ethylene or propylene may be used), (polyoxyalkylene) polysilalate, (polyoxyalkylene) polyester, and (polyoxyalkylene) polyphosphate.

[0056] As a second anionic polymerization accelerator, a crown ether or its derivatives can be mentioned, and the known compounds such as disclosed in U.S. Pat. No. 4,171,416, Japanese Unexamined Patent Publication (Kokai) No. 3-167279,. and others can all be used. Specific examples of the crown ether or its derivatives include the followings:

[0057] Crown ether and its derivatives

[0058] 15-crown-5, 18-crown-6, dibenzo-18-crown-6, benzo-15-crown-5, dibenzo-24-crown-8, dibenzo-30-crown-10, tribenzo-18-crown-6, asym-dibenzo-22-crown-6, dibenzo-14-crown-4, dicyclohexyl-18-crown-6, dicyclohexyl-24-crwon-8, cyclohexyl-12-crown-4, 1,2-decalyl-15-crown-5, 1,2-naphtho-15-crown-5, 3,4,5-naphthyl-16-crown-5, 1,2-methylbenzo-18-crown-6, 1,2-methylbenzo-5,6-methylbenzo-18-crown-6, 1,2-tert-butyl-18-crown-6, 1,2-vinylbenzo-15-crown-5, 1,2-vinylbenzo-18-crown-6, 1,2-tert-butylcyclohexyl-18-crown-6, and 1,2-benzo-1,4-benzo-5-oxygen-20-crown-7.

[0059] As a third anionic polymerization accelerator, a silacrown or its derivatives can be mentioned, and the compounds disclosed in Japanese Examined Patent Publication (Kokoku) No. 62-31034 and Japanese Unexamined Patent Publication (Kokai) No. 60-168775 can all be used. Specific examples of such compounds include the followings:

[0060] Silacrown compounds

[0061] Dimethylsila-11-crown-4, dimethylsila-14-crown-5, and dimethylsila-17-crown-6.

[0062] As a fourth anionic polymerization accelerator, calixalene derivatives can be mentioned, and the known compounds such as disclosed in Japanese Unexamined Patent Publication (Kokai) Nos. 60-179482, 62-235379, and 63-88152 can all be used.

[0063] Specific examples of the compounds include ones represented by formulas (1) and (2).

[0064] wherein R¹ represents alkyl, alkoxy, substituted alkyl, or substituted alkoxy group, R² represents hydrogen atom or alkyl group, and n represents 4, 6, or 8.

[0065] wherein both m and n are integers and satisfy an equation, m+n=4, 6 or 8, and equation, n≦½(m+n). R³ represents hydrogen atom, or hydrocarbyl or substituted hydrocarbyl group. R⁴ represents hydrogen atom, or hydrocarbyl, aryl, hydrocarbyl aryl, substituted hydrocarbyl, substituted aryl, or substituted hydrocarbyl aryl group. R⁵ represents aryl, hydrocarbyl aryl, allyloxy, hydrocarbyl allyloxy, substituted aryl, substituted hydrocarbyl aryl, substituted allyloxy, or substituted hydrocarbyl allyloxy group. When R⁴ is aryl, hydrocarbyl aryl, substituted aryl, or substituted hydrocarbyl aryl group, R⁵ is hydrocarbyl, hydrocarbyloxy, substituted hydrocarbyl, or substituted hydrocarbyloxy group.

[0066] As a fifth anionic polymerization accelerator, a cyclosulfur compound can be mentioned, and the known compounds disclosed, for example, in Japanese Unexamined Patent Publication (Kokai) No. 59-64681 can all be used. They are cyclosulfur compounds having polysulfide linkage and ether linkage in the molecule, and represented by formula (3).

[0067] wherein R⁶ and R⁷ represent hydrocarbon chain having 2 to 6 carbon atoms, m represents an integer of 2 to 4, and n represents an integer of 1 to 3.

[0068] The amount of the anionic polymerization accelerator to be added is preferably 10 to 100,000 ppm, more desirably 30 to 10,000 ppm based on a cyanoacrylate adhesive composition.

[0069] When the amount of the anionic polymerization accelerator to be added is smaller than 10 ppm, rapid cureability of the adhesive can hardly be obtained, while when the amount exceeds 100,000 ppm, the bonding strength and storage stability of the adhesive considerably decrease and much improvement in cureability is no longer expected.

[0070] As in conventional cyanoacrylate adhesives, it is preferable to include a very small quantity of, for example, hydroquinone or sulfurous acid gas as a polymerization inhibitor in the cyanoacrylate adhesive composition of the present invention to improve the storage stability.

[0071] While 2-cyanoacrylate is inherently a colourless, transparent liquid substance having a low viscosity, a better effect can be obtained when it is made into a viscous or thixotropic liquid by dissolving or dispersing a thickener such as polymethyl methacrylate, acrylic rubber, cellulose derivative, and fumed silica in the present adhesive composition.

[0072] Further, the cyanoacrylate adhesive composition of the present invention can be coloured by a specific dye.

[0073] While any mechanism has not yet been elucidated, the cyanoacrylate adhesive composition of the present invention exhibits a very remarkable behavior that it shows an excellent instantaneous adhesive property for adherends other than the skin, such as woods, plastics, rubbers, metals, and ceramics, but does not show the instantaneous adhesion property for the skin.

[0074] The cyanoacrylate adhesive composition of the present invention will decrease the trouble of “skin adhesion” upon adhesion operation. Thus, the cyanoacrylate adhesive composition of the present invention has advantages that it can widely be used in more applications than conventional cyanoacrylate adhesives and that it can be used more safely in a house or school for bonding stationery as well as in various industries, medical fields and leisure fields.

EXAMPLES

[0075] Now the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to such specific Examples.

Examples 1 through 38

[0076] Adhesion tests were conducted by using various kinds of adherends shown in Table 1 and fingers of individuals shown in Table 2 with the adhesives shown in Tables 3, 4, 5, and 6. TABLE 1 Adherend Producer Size Rigid polyvinyl Japan Test Panel In accordance with chloride Kogyo Kabushiki JIS K 6849 Kaisha Balsa Japan Test Panel In accordance with Kogyo Kabushiki JIS K 6850 Kaisha Chloroprene rubber Japan Test Panel In accordance with Kogyo Kabushiki JIS K 6850 Kaisha

[0077] TABLE 2 Individual who conducted test Distinction of sex Age A Male 23 B Male 35 C Male 52 D Female 23

[0078] TABLE 3 2-cyanoacrylic Polymerization acid ester Alcohol Additive Stabilizer accelerator Example (wt %) (wt %) (wt %) (ppm) (ppm) 1 Ethyl ester 70 n-hexanol 30 SO₂ 20 18-crown-6 200 HQ 500 2 Ethyl ester 70 n-octanol 30 SO₂ 20 18-crown-6 200 HQ 500 3 Ethyl ester 70 Decanol 30 SO₂ 20 18-crown-6 200 HQ 500 4 Ethyl ester 75 Tridecanol 25 SO₂ 20 18-crown-6 200 HQ 500 5 Ethyl ester 70 Tridecanol 30 SO₂ 20 18-crown-6 200 HQ 500 6 Ethyl ester 70 Oxocol 1213 20 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 AEROSIL R974 6.3 HQ 500 7 Ethyl ester 77 Oxocol 1213 23 SO₂ 20 18-crown-6 200 HQ 500

[0079] TABLE 4 2-cyanoacrylic Polymerization acid ester Alcohol Additive Stabilizer accelerator Example (wt %) (wt %) (wt %) (ppm) (ppm)  8 Ethyl ester 80 Oxocol 20 SO₂ 20 18-crown-6 200 HQ 500  9 Ethyl ester 77 Oxocol 1215 23 SO₂ 20 18-crown-6 200 HQ 500 10 Ethyl ester 70 n-hexanol 30 SO₂ 20 Dimethyl- 5000 HQ 500 sila-17 crown-6 11 Ethyl ester 70 n-octanol 30 SO₂ 20 Calixalene 5000 HQ 500 #1 12 Ethyl ester 70 Decanol 30 SO₂ 20 Calixalene 5000 HQ 500 #2 13 Ethyl ester 75 Tridecanol 25 SO₂ 20 Cyclosulfur 1000 HQ 500 compound

[0080] TABLE 5 Aliphatic 2-cyanoacrylic carboxylic Polymerization acid ester acid ester Additive Stabilizer accelerator Example (wt %) (wt %) (wt %) (ppm) (ppm) 14 Ethyl ester 80 Methyl 20 SO₂ 20 18-crown-6 200 laurate HQ 500 PEG 2000 2000 15 Ethyl ester 74 Bis(2- 23 Acrylic polymer 3 SO₂ 20 18-crown-6 500 ethylhexyl) HQ 500 adipate 16 Ethyl ester 80 Coconard 10 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 MT AEROSIL R974 6.3 HQ 500 17 Ethyl ester 74 Diisobutyl 23 Acrylic polymer 3 SO₂ 20 18-crown-6 200 fumarate HQ 500 PEG 2000 2000 18 Ethyl ester 80 Methyl 20 SO₂ 20 Dimethyl- 5000 laurate HQ 500 sila-17- crown-6 19 Ethyl ester 74 Bis(2- 23 Acrylic polymer 3 SO₂ 20 Calixalene 1000 ethylhexyl) HQ 500 #1 adipate 20 Ethyl ester 80 Coconard 10 Acrylic polymer 3.7 SO₂ 20 Calixalene 5000 MT AEROSIL R974 6.3 HQ 500 #2 21 Ethyl ester 74 Diisobutyl 3 Acrylic polymer 3 SO₂ 20 Cyclosulfur 1000 fumarate HQ 500 compound 22 Ethyl ester 70 Tributyl 30 SO₂ 20 18-crown-6 200 acetylcitrate HQ 500 23 Ethyl ester 70 Dibutyl 30 SO₂ 20 18-crown-6 200 adipate HQ 500 24 Ethyl ester 85 Coconard 15 SO₂ 20 18-crown-6 200 MT HQ 500 25 Ethyl ester 79 Coconard 15 Acrylic polymer 6 SO₂ 20 18-crown-6 200 MT HQ 500 26 Ethyl ester 75 Coconard 15 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 MT AEROSIL R974 6.3 HQ 500

[0081] TABLE 6 Carbocyclic 2-cyanoacrylic carboxylic Polymerization acid ester acid ester Additive Stabilizer accelerator Example (wt %) (wt %) (wt %) (ppm) (ppm) 27 Ethyl ester 70 Bis(2- 30 SO₂ 20 18-crown-6 200 ethylhexyl) HQ 500 PEG 2000 2000 phthalate 28 Ethyl ester 80 Diisononyl 10 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 phthalate AEROSIL R974 6.3 HQ 500 PEG 4000 500 29 Ethyl ester 70 Tris(2- 20 Acrylic polymer 3.7 SO₂ 20 18-crown-6 500 ethylhexyl AEROSIL R974 6.3 HQ 500 trimellitate 30 Ethyl ester 79 Tris(2- 16.7 Acrylic polymer 4.3 SO₂ 20 18-crown-6 500 ethylhexyl HQ 500 trimellitate 31 Ethyl ester 70 Bis(2- 30 SO₂ 20 Dimethyl- 5000 ethylhexyl HQ 500 sila- 17-crown-6 32 Ethyl ester 80 Diisononyl 10 Acrylic polymer 3.7 SO₂ 20 Calixalene 1000 phthalate AEROSIL R974 6.3 HQ 500 #1 33 Ethyl ester 70 Tris(2- 20 Acrylic polymer 3.7 SO₂ 20 Calixalene 5000 ethylhexyl AEROSIL R974 6.3 HQ 500 #2 trimellitate 34 Ethyl ester 79 Tris(2- 16.7 Acrylic polymer 4.3 SO₂ 20 Cyclosulfur 1000 ethylhexyl HQ 500 compound trimellitate 35 Ethyl ester 80 Diisononyl 10 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 phthalate AEROSIL R976 6.3 HQ 500 36 Ethyl ester 75 Diisononyl 15 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 phthalate AEROSIL R976 6.3 HQ 500 37 Ethyl ester 80 Bis(2- 10 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 ethylhexyl AEROSIL R976 6.3 HQ 500 phthalate 38 Ethyl ester 75 Bis(2- 15 Acrylic polymer 3.7 SO₂ 20 18-crown-6 200 ethylhexyl AEROSIL R976 6.3 HQ 500 phthalate

[0082] Decanol, tridecanol, Oxocol 1213, and Oxocol 1215 in Tables 3 to 6 were produced by Kyowa Hakko Kogyo Co., Ltd., and Coconard MT is a triglyceride having 8 to 10 carbon atoms, produced by Kao Corporation.

[0083] Calixalene #1 as a polymerization accelerator is 37,38,39,40,41,42-hexa-(2-oxo-2-ethoxy)-etoxycalics [6] allene, calixalene #2 is a compound represented by formula (4), and a cyclosulfur compound is one represented by formula (5).

[0084] Evaluation tests were conducted by the methods as follows:

[0085] (1) Method for determining set time:

[0086] (Rigid polyvinyl chloride)

[0087] Test specimens of rigid polyvinyl chloride were pasted together with an adhesive in accordance with the method of JIS K 6849 and the time when the bonding strength reaches a value of higher than 3 kg was assumed to be the set time.

[0088] (Balsa, chloroprene rubber)

[0089] Test specimens were pasted together with an adhesive in accordance with the method of JIS K 6850 and the time when the bonding strength reaches such a degree that the test specimens can not be detached by lightly pulling them by hands toward the direction of a major axis of the test specimens was assumed to be the set time.

[0090] (Finger)

[0091] An adhesive was applied on the surface of a forefinger, the adhesive was spreaded to form a thin film by pressing lightly with a thumb, and the time (t) when the forefinger is separated from the thumb by their own ability without pain, was determined at 5 ranks of

[0092] t≦1 sec,

[0093] 1 sec<t≦15 sec,

[0094] 15 sec<t≦30 sec,

[0095] 30 sec<t≦60 sec, and

[0096] 60 sec<t.

[0097] Environment for the determination was adjusted to a temperature of 23° C. and humidity of 60% RH.

[0098] The results of the tests are shown in Tables 7, 8, and 9. TABLE 7 Set time (sec) Rigid Finger set time (sec) polyvinyl Chloroprene Example A B C D chloride Balsa rubber 1 15-30 30-60 30-60 30-60 10 15 45 2 30-60 60< 60< 60< 3 10 30 3 60< 60< 60< 60< 10 20 60 4 60< 60< 60< 60< 3 15 15 5 60< 60< 60< 60< 3 30 20 6 15-30 60< 30-60 60< 3 10 15 7 60< 60< 60< 60< 10 20 30 8 30-60 60< 60< 60< 10 20 20 9 60< 60< 60< 60< 15 30 30 10  15-30 30-60 30-60 30-60 10 25 45 11  30-60 60< 60< 60< 3 15 30 12  60< 60< 60< 60< 10 20 60 13  60< 60< 60< 60< 3 25 30

[0099] TABLE 8 Set time (sec) Rigid Finger set time (sec) polyvinyl Example A B C D chloride Balsa 14 60< 60< 60< 60< 3 7 15 60< 60< 60< 30-60 5 10 16 60< 60< 60< 30-60 5 7 17 60< 60< 60< 30-60 5 7 18 30-60 60< 60< 30-60 5 7 19 60< 60< 60< 30-60 10 10 20 60< 60< 60< 30-60 5 10 21 60< 60< 60< 30-60 5 7 22 60< 60< 60< 60< 5 — 23 60< 60< 60< 60< 5 — 24 15-30 15-30 15-30 15-30 5 — 25 60< 60< 60< 60< 5 — 26 60< 60< 60< 60< 5 —

[0100] TABLE 9 Set time (sec) Rigid Finger set time (sec) polyvinyl Example A B C D chloride Balsa 27 60< 60< 60< 60< 3 3 28 60< 60< 60< 60< 3 3 29 60< 60< 60< 60< 5 10 30 60< 60< 60< 60< 3 3 31 60< 60< 60< 60< 5 7 32 60< 60< 60< 60< 7 10 33 60< 60< 60< 60< 7 10 34 60< 60< 60< 60< 5 7 35 60< 60< 60< 60< 3 — 36 60< 60< 60< 60< 3 — 37 30-60 30-60 30-60 30-60 3 — 38 60< 60< 60< 60< 3 —

Comparative Examples 1 through 17

[0101] Examples were repeated except that the adhesives shown in Table 10, 11, and 12 were used. The results of the comparative tests are shown in Tables 13, 14, and 15. TABLE 10 Compara- 2-cyanoacrylic Polymerization tive acid ester Alcohol Additive Stabilizer accelerator Example (wt %) (wt %) (wt %) (ppm) (ppm) 1 Ethyl ester 100 SO₂ 20 18-crown-6 200 HQ 500 2 Ethyl ester 100 SO₂ 20 HQ 500 3 Ethyl ester 80 Butyl 20 SO₂ 20 18-crown-6 200 alcohol HQ 500 4 Ethyl ester 70 Butyl 30 SO₂ 20 18-crown-6 200 alcohol HQ 500 5 Ethyl ester 80 Ethyl 20 SO₂ 20 18-crown-6 200 alcohol HQ 500 6 Ethyl ester 70 Ethyl 30 SO₂ 20 18-crown-6 200 alcohol HQ 500

[0102] TABLE 11 Aliphatic Compara- 2-cyanoacrylic carboxylic Polymerization tive acid ester acid ester Additive Stabilizer accelerator Example (wt %) (wt %) (wt %) (ppm) (ppm)  7 Ethyl ester 80 Methyl 20 SO₂ 20 laurate HQ 500  8 Ethyl ester 80 Butyl 20 SO₂ 20 18-crown-6 200 acetate HQ 500  9 Ethyl ester 70 Butyl 30 SO₂ 20 18-crown-6 200 acetate HQ 500 10 Ethyl ester 70 n-amyl 30 SO₂ 20 18-crown-6 200 acetate HQ 500 11 Ethyl ester 70 n-butyl 30 SO₂ 20 18-crown-6 200 acrylate HQ 500 12 Ethyl ester 70 Dimethyl 30 SO₂ 20 18-crown-6 200 succinate HQ 500 13 Ethyl ester 70 Diethyl 30 SO₂ 20 18-crown-6 200 succinate HQ 500 14 Ethyl ester 80 Diisopropyl 30 SO₂ 20 18-crown-6 200 malonate HQ 500

[0103] TABLE 12 Aliphatic Compara- 2-cyanoacrylic carboxylic Polymerization tive acid ester acid ester Additive Stabilizer accelerator Example (wt %) (wt %) (wt %) (ppm) (ppm) 15 Ethyl ester 70 Dimethyl 30 SO₂ 20 18-crown-6 200 phthalate HQ 500 16 Ethyl ester 70 Dimethyl 30 SO₂ 20 18-crown-6 200 phthalate HQ 500 17 Ethyl ester 70 Bis(2- 30 SO₂ 20 ethylhexyl) HQ 500 phthalate

[0104] TABLE 13 Set time (sec) Compara- Rigid tive Finger set time (sec) polyvinyl Example A B C D chloride Balsa 1 <1 <1 <1 <1 3 7 2 <1 <1 <1 <1 10   60< 3 <1 <1 <1 <1 2 10 4 1-15 1-15 1-15 1-15 3 10 5 <1 <1 <1 <1 2  5 6 1-15 1-15 1-15 1-15 3 10

[0105] TABLE 14 Set time (sec) Compara- Rigid tive Finger set time (sec) polyvinyl Example A B C D chloride Balsa  7 60< 60< 60< 60< 30   60<  8 <1  <1  <1  <1  3  5  9 1-15 1-15 1-15 1-15 5 10 10 1-15 1-15 1-15 1-15 5 10 11 1-15 1-15 1-15 1-15 5 15 12 1-15 1-15 1-15 1-15 5 10 13 1-15 1-15 1-15 1-15 5 15 14 1-15 1-15 1-15 1-15 5 15

[0106] TABLE 15 Set time (sec) Compara- Rigid tive Finger set time (sec) polyvinyl Example A B C D chloride Balsa 15 <1  <1  <1  <1  5 10 16 1-15 1-15 1-15 1-15 5  7 17 60< 60< 60< 60< 10   60< 

1. A cyanoacrylate adhesive composition having a lowered adhesion to the skin, containing at least one compound selected from the groups A-D mentioned below and an anionic polymerization accelerator: A: An aliphatic alcohol having an aliphatic group in which 6 or more carbon atoms are directly bonded with each other; B: An aliphatic carboxylic acid ester having an aliphatic group in which 6 or more carbon atoms are directly bonded with each other; C: An aliphatic carboxylic acid ester having at least 2 aliphatic groups in which 4 or more carbon atoms are directly bonded with each other; and D: A carboxylic acid ester of a carbocyclic compound having, in a carboxylic acid residue or alcohol residue, an aliphatic group in which 5 or more carbon atoms are directly bonded with each other.
 2. The cyanoacrylate adhesive composition according to claim 1 , wherein the aliphatic alcohol under the Group A has an aliphatic group in which 9 or more carbon atoms are directly bonded with each other.
 3. The cyanoacrylate adhesive composition according to claim 2 , wherein the aliphatic alcohol under the Group A is decanol, tridecanol, or lauryl alcohol.
 4. The cyanoacrylate adhesive composition according to claim 1 , wherein the aliphatic carboxylic acid ester under the Group B has an aliphatic group in which 8 or more carbon atoms are bonded each other.
 5. The cyanoacrylate adhesive composition according to claim 4 , wherein the carboxylic acid ester under the Group B is methyl laurate, dimethyl sebacate, octyl acrylate, or decyl methacrylate.
 6. The cyanoacrylate adhesive composition according to claim 1 , wherein the aliphatic carboxylic acid ester under the group C has at least 3 aliphatic groups in which 4 or more carbon atoms are directly bonded with each other.
 7. The cyanoacrylate adhesive composition according to claim 6 , wherein the aliphatic carboxylic acid ester under the Group C is tributyl acetylcitrate.
 8. The cyanoacrylate adhesive composition according to claim 1 , wherein the carboxylic acid ester under the Group D is an ester of phthalic acid or trimellitic acid.
 9. The cyanoacrylate adhesive composition according to claim 1 , wherein the carboxylic acid ester of a carbocyclic compound under the Group D has, in the carboxylic acid residue or alcohol residue, an aliphatic group in which 8 or more carbon atoms are directly bonded with each other.
 10. The cyanoacrylate adhesive composition according to claim 9 , wherein the carboxylic acid ester under the Group D is bis(2-ethylhexyl) phthalate or tris(2-ethylhexyl) trimellitate.
 11. The cyanoacrylate adhesive composition according to claim 1 , wherein the carboxylic acid ester under the Group D has, in the carboxylic acid residue or alcohol residue, an aliphatic group in which 9 or more carbon atoms are directly bonded with each other.
 12. The cyanoacrylate adhesive composition according to claim 11 , wherein the carboxylic acid ester under the Group D is diisononyl phthalate, diisodecyl phthalate, or diisotridecyl phthalate.
 13. The cyanoacrylate adhesive composition according to claim 1 , wherein the composition further contains a polymer or copolymer of an acrylate or methacrylate.
 14. The cyanoacrylate adhesive composition according to claim 13 , wherein the polymer or copolymer of an acrylate or methacrylate is polymethyl methacrylate, polybutyl methacrylate, or a copolymer of methyl methacrylate with an acrylate.
 15. The cyanoacrylate adhesive composition according to claim 1 , wherein the composition further contains a fumed silica. 